This invention relates to surgical stapling apparatus, and more particularly to surgical stapling apparatus for substantially simultaneously driving a plurality of surgical staples through body tissue and against an anvil to produce an array of crimped staples in the body tissue.
Surgical staplers in which a plurality of surgical staples are driven substantially simultaneously from a staple holder to produce an array of staples in body tissue are known. Typically these staplers include a staple holder disposed on one side of the tissue to be stapled, an anvil parallel to the staple holder on the other side of the tissue to be stapled, means for linearly translating the staple holder and the anvil toward one another so that the tissue is clamped between them, and means for driving the staples from the staple holder so that the ends of the staples pass through the tissue and are crimped against the anvil, therey producing an array of finished staples in the tissue. In common use are staplers in which the staple holder and anvil comprise a disposable cartridge removably mounted in or on a permanent actuator for supporting and actuating the cartridge. The cartridge is disposable after a single use. The permanent actuator is reusable in the same surgical procedure after reloading with a fresh cartridge, and is reusable in another surgical procedure after cleaning, sterilizing, and reloading.
Because of the difficulty and expense of cleaning and sterilizing surgical instruments, there is increasing interest in and demand for disposable surgical instruments. This is especially true of surgical instruments having a number of moving parts such as the surgical stapler actuators mentioned above. On the other hand, the actuators in prior surgical staplers have generally been required to withstand relatively large forces associated with clamping the tissue to be stapled and driving a plurality of staples through the tissue, while at the same time providing the precise alignment between the staple holder and anvil which is required for proper staple formation. These requirements have typically necessitated very rigid actuator structures including substantial numbers of precision parts made of relatively expensive materials such as stainless steel. Such structures are generally not economically disposable.
It is therefore an object of this invention to provide surgical stapling apparatus of the type described above in which the requirements for rigidity and precision in the actuator are substantially relaxed so that the actuator can be made using a higher proportion of relatively inexpensive materials and in a relatively inexpensive design, thereby making the actuator (as well as the cartridge) economically disposable if desired.
Although instruments of the type described above are available for performing several different types of surgical stapling procedures requiring instruments and staple arrays of various configurations, an illustrative type of instrument is the so-called thoracic-abdominal surgical stapler, which is typically used for forming a row of staples laterally through hollow body organs such as the thorax, trachea, stomach, or intestines. Staplers of this type generally have a U-shaped structure at the distal end of the instrument which is positioned around the tissue to be stapled. The anvil, which in this type of instrument is a longitudinal member, is mounted on the distal leg of the U-shaped structure, while the staple holder is mounted relative to the proximal leg of the structure. A knob at the proximal end of the instrument allows the staple holder to be translated toward the anvil to clamp the tissue between the opposing faces of the anvil and the staple holder. Thereafter, a handle mechanism also associated with the proximal portion of the instrument is operated to simultaneously drive all of the staples out of the staple holder through the tissue and against the anvil. When the tissue has thus been stapled, the clamping knob is operated again to retract the now empty staple holder, thereby releasing the tissue from the instrument.
A problem associated with instruments of this type (and to various degrees with other similar types of surgical staplers) is that the large forces acting on the U-shaped structure at the distal end of the instrument as a result of clamping the tissue in that structure and simultaneously driving a large number of staples between the parallel legs of that structure can cause the structure to deform. In particular, the parallel legs of the U-shaped structure may be forced apart and thereby lose their parallelism. The distal leg of the U-shaped structure may also be shifted longitudinally relative to the proximal leg as a result of deformations in the base of the U-shape and elsewhere in the structure. These deformations or strains in the U-shaped structure can occasionally cause the staple holder and the anvil to become misaligned to such a degree that the anvil no longer crimps some or all of the staples properly. The improperly crimped staples may not adequately staple the tissue and/or may injure the tissue.
It is therefore another object of this invention to provide surgical stapling apparatus of the type described above in which misalignment of the staple holder and anvil due to deformation of the associated support structure is substantially reduced or eliminated.